Convective Outlook

[Coast]

New discussion here for the convective outlook

[Crimson_Sprite]

ahh right, thanks Coast. I knew what CAPE and Lift were all about , but I just didnt know what the value of the gray coloured areas on your CAPE map were indicating. I have like a 12 for CAPE hahaha and even worse lift, so am not expecting any storms, but was hoping with everything I got that some mental possibility was there..

[Harry]

I've been keeping an eye on the charts and there is going to be some very exciting stuff happening just across the Channel from us in the next 36-48 hours! Looking like there's going to be some really quite intense thunderstorms across N France tomorrow and Wednesday, with the LP triggering them TRYING to push towards us...I found this chart very interesting (if a little hopeful) but might be worth keeping an eye on...the pressure charts are all over the place so I am not quite sure what is going to happen....

The northerly seems to be delayed some what further South as this LP system skirts across - not 100% sure it's going to be as cool tomorrow in the South as they are forecasting - hopefully that LP system will track slightly further north

Edited May 24, 2010 by Harry

[staplehurst]

I've been keeping an eye on the charts and there is going to be some very exciting stuff happening just across the Channel from us in the next 36-48 hours! Looking like there's going to be some really quite intense thunderstorms across N France tomorrow and Wednesday, with the LP triggering them TRYING to push towards us...I found this chart very interesting (if a little hopeful) but might be worth keeping an eye on...the pressure charts are all over the place so I am not quite sure what is going to happen....

I've been watching that for a few days now, and it looks like tomorrow night might see a slim risk of a few storms clipping Kent - shame I'm in Norfolk at the moment!

Does look like some big storms in France though.

[Harry]

I've been watching that for a few days now, and it looks like tomorrow night might see a slim risk of a few storms clipping Kent - shame I'm in Norfolk at the moment!

Does look like some big storms in France though.

I've only just seen the GFS and how much it has changed from earlier - over 3000 CAPE progged for C/N belt of France...going to be at the very least an Estofex Level 2 for them tomorrow I'd imagine - I might even zip down to the coast tomorrow evening (though will see how this develops further) - come on change a bit further for us to nip in on a bit of the action

[ZONE 51]

hi all small chance of a development later across se england as the breezes meet across the se , something may just spark off i think .

[Stormyking]

I've only just seen the GFS and how much it has changed from earlier - over 3000 CAPE progged for C/N belt of France...going to be at the very least an Estofex Level 2 for them tomorrow I'd imagine - I might even zip down to the coast tomorrow evening (though will see how this develops further) - come on change a bit further for us to nip in on a bit of the action

Hmm im wonder whether it will be worth for me to pop down the sea front or up on culver downs hopefully I might get lucky and see some distant lightning looking at that rain chart looks possible .

[Mesoscale]

Im hopeing something gets sparked off here tonight, i wouldnt mind this hot snap going out with a bang today has been the hottest of all of them.

As for france tommorow it looks good if not a little bit scary with the CAPE going to be so high.

Lets hope for that plume event early june!

[Harry]

Latest GFS run has ever so slightly shunted some of the storm risk for tomorrow night slightly North in to the Channel, while later on Wednesday the occlusion swings up across the SE with some potential for heavy rain.

Appears to be a foci for some very high CAPE/LI values between Calais and Le Havre tomorrow afternoon - should it be realised (looks likely) could get some nice cloud scapes from the south coast (should the skies be quite clear)

See image below - how close do we need to be!! poxy HP lol

Edited May 24, 2010 by Harry

[staplehurst]

Latest GFS run has ever so slightly shunted some of the storm risk for tomorrow night slightly North in to the Channel, while later on Wednesday the occlusion swings up across the SE with some potential for heavy rain.

Appears to be a foci for some very high CAPE/LI values between Calais and Le Havre tomorrow afternoon - should it be realised (looks likely) could get some nice cloud scapes from the south coast (should the skies be quite clear)

See image below - how close do we need to be!! poxy HP lol

There is still some disagreement between the UKMO High Res and the GFS, UKMO is keen to throw some potent cells in the channel and clip E Sussex/Kent tomorrow evening, GFS keeps all precip over France until Wednesday itself. Thing is UKMO and GFS are both being persistent in their positioning - one of them has to give eventually!

[staplehurst]

In the end it was the UKMO model to step down and fall back in line with GFS - interesting...

[pottyprof]

Just been stood watching an amazing rotating updraught. Certainly some big stuff going up around here.. Don't think it'll produce anything other than a shower though.

Edit. That said, some very rapid convection starting to happen now. Looking black over Bill's mother's

[Andy Bown]

An intriguing change in the forecast for the West Country on this evening's BBC Points West forecast. Ian Fergusson (a NW poster during the winter) showing heavy showers developing across South Somerset and Dorset tomorrow late afternoon.

[Mesoscale]

I got sooo excited when i saw this on the bbc weather website but then i looked closer and noticed it had aprill in there and the date was 29/04/2005, I was like yeah a spanish plume event finally and on the bank holiday aswell but no the weather continues to tease me

Building heat in western Europe could make it a thundery Bank Holiday by Dan Corbett

Building heat in western Europe could make it a thundery Bank Holiday

It has definitely been shorts weather across western Europe over the past couple of days. On Thursday the afternoon highs across parts of France and Spain were well into the 20 and 30’s Celsius. Bordeaux, France reached 28C (82F), well over 17C (63F), its normal in April, while in Zaragoza, Spain the temperature climbed to 31C (88F) well above it’s average of 23C (73F) in April.

The warmer than normal readings over western Europe have been triggered by a big ridge of high pressure sitting across southern Spain. Southerly winds have brought in warmer air from northern Africa.

All that warm air will head north and spread over the UK to make it a pleasant bank holiday weekend for many. Will it actually be a warm bank holiday across the UK? It probably sounds too good to be true and it is a bit more complicated than that.

A familiar summertime weather situation could set up this weekend over western Europe called a Spanish plume. A Spanish plume is where warm thundery air moves up from Spain and brings thunderstorms to northwest Europe. This sort of situation could happen across the UK this weekend.

A Spanish plume is actually made up with several different key ingredients.

The warm air will move across the UK in two parts. The first area of warm air will be the warm and humid air that will move in from France on Saturday. The second will be warm but drier air from the plateaus of Spain. This area of warm air from Spain will move in above the warm and humid air from France.

The final ingredient to help bring us the risk of thundery showers for the Bank holiday weekend will be a trigger moving in from the Atlantic over the weekend. This trigger will come in the form of an upper level weather disturbance that will cool the upper levels of the atmosphere and make the air across the UK more unstable. This will set the scene for possible thunderstorms across much of the UK on Sunday into Monday. Fingers crossed these storms that do develop will be scattered so we won’t see rain all the time everywhere..

Sorry if this confused you guys aswell haha I didnt mean to!

[Harry]

I got sooo excited when i saw this on the bbc weather website but then i looked closer and noticed it had aprill in there and the date was 29/04/2005, I was like yeah a spanish plume event finally and on the bank holiday aswell but no the weather continues to tease me

Sorry if this confused you guys aswell haha I didnt mean to!

It's a very useful reminder why humid air alone doesn't necessarily mean thunderstorms!

I.e in the spanish plume scenario, the fact you need that lid of dry air from the plateau to really set up the powder keg, with the third a final component, 'the trigger' to light that fuse! All we've had the last few days has really been warm and relatively humid air - no real definition between dry and moisture and certainly no trigger, hence the real lack of convective weather...

Roll on a plume...seriously love 'em!!

[Guest FireStorm]

I'll happily take a Spanish plume with French aiding for a storm setup!

[Nick F]

Yep, some impressive CAPE/LI across parts of France tomorrow, thanks to some moist air pooling (dew points reaching 64F) and temps reaching 80F+. Would expect some large hail from storms that develop. Deep layer shear only in the order of 30 knts and not much in the way of low level shear but wind convergence ahead of developing cold front moving east and high CAPE values may be sufficient for a tornado or two.

Looks like storms/instability will stay over France unfortunately, though we may see some heavy thundery rain clipping the south coast of England tomorrow night/Weds morning as the occlusion around the low moving E across N France slides east along the English Channel.

Looks like it will turn increasingly convective across the north by the end of the week, as low and upper cold pool moves across Scotland, then during the weekend it looks like moving south down the eastern side of the UK, bringing south the threat of heavy showers and perhaps thunderstorms across parts of England too.

[Harry]

I suppose it would be foolish to just hope that the LP causing the outbreak across France may just slip slightly further North

Will be jumping on the web tomorrow morning though to check either way lol...but I know it's going to be painful seeing the Estofex zones running tightly along the N France border...to quote a special video posted on here last year, "frogs will get all the fun again"

[StormChaseUK]

I suppose it would be foolish to just hope that the LP causing the outbreak across France may just slip slightly further North

Will be jumping on the web tomorrow morning though to check either way lol...but I know it's going to be painful seeing the Estofex zones running tightly along the N France border...to quote a special video posted on here last year, "frogs will get all the fun again"

Harry, been reading your updates with interest.

I noticed the bbc main forecast were mentioning "thunderstorms dartmoor, devon end of the day" for tuesday/tomorrow

Will need watching tomorrow morning, to see how things progress - but anyone venturing down to the south coast tomorrow may catch some excellent fireworks

out to sea after 10pm I would say.

Def one to watch

[Coast]

Well, ESTOFEX showing that area of interest just over the Channel - will it or won't it get as far as our shores later ????

Storm Forecast

Valid: Tue 25 May 2010 06:00 to Wed 26 May 2010 06:00 UTC

Issued: Mon 24 May 2010 23:05

Forecaster: KOROSEC

A level 1 was issued for south-central France, NW Switzerland and SW Germany mainly for large hail and excessive convective rainfall.

SYNOPSIS

A quite complex scenario unfolds across Europe on Tuesday. There is a large deep trough over northern Europe while a kind of omega like pattern over southern Europe slowly wipes out while making eastwards progress. There, two upper lows are located on both of its flanks. The western upper low moves into western Europe while merges with the main trough towards the Wednesday morning. The second, weaker upper low moves NE-wards from extreme southern Mediterranean into extreme SE Europe.

At surface, a cold front associated with the northern large trough moves further SE across east-central Europe while slowly weakening. The frontal boundary stays quasi-stationary over central Europe where its western flank transforms/merges with the warm front advecting across France. The frontal system pushes the cold front into western France.

UKASF Have a watch zone down here on the South Coast:

Storm Forecast Issued: 2010-05-24 23:33:00

Valid: 2010-05-25 00:00:00 - 2010-05-25 23:59:00

Regions Affected

(CS, SW & SE England included in the WATCH)

Synopsis

An area of HIGH pressure to the northwest of the United Kingdom, and a developing broad area of LOW pressure over Biscay, will dominate the weather on Tuesday.

A cool but stable northerly flow becomes established across the United Kingdom, so very little activity is expected. However, attention turns to the boundary between the cool airmass and the hot and humid airmass, which will be present over northern France. This, coupled with cyclogenesis, will provide focus for numerous thunderstorms to develop along the warm, cold and occluded fronts across this region during the afternoon. Such storms are likely to turn supercellular at times, capable of producing a weak-moderate tornado.

Consistent trends are for these to move northeastwards during the afternoon and evening, moving across southern portions of the English Channel but staying offshore from mainland Britain. There is a very low risk of these grazing the south coast (<10% chance). Also, there is a low risk of an isolated thunderstorm over parts of Southwest England (<30% chance) during the late afternoon/evening.

We will monitor the situation during Tuesday.

Nothing from TORRO so here are some charts for further analysis and discussion:

I think I shall take a drive up to Beachy Head later to check out the action over the Channel towards France as I'm not sure it will get to us here:

[Harry]

It comes so tantalisingly close that seems to have become the case now over the last few years - depressingly close but no cigar! Might catch a few flashes of lightning later tonight if the skies remain clear our end.

[Coast]

Already sferics in the Bay Of Biscay. DP's are looking OK here and over the puddle:

[Harry]

Latest GFS ramps up the CAPE, Lifted Indices and Storm Risk across Northern France (3000+ J/Kg CAPE, LI's of -8!! )...there could be some stunning skylines from the south coast later - still upset it's going to stay away from us!

[Harry]

Yes, interesting day ahead for a good part of France and would love to be there. Perhaps some marginally severe thunderstorms during evening period as wind speed increases with height so some organized cells developing across central and then eastern France later on today and into tomorrow. Can expect high amounts of lightning and some large hail given storms' organization and height- given MLCAPE values of perhaps 2000j/kg by evening time across parts of France.

Back here and models not showing anything of note concerning potential for thunderstorms.

I wouldn't rule out an isolated shower/storm down across the SW

[Stormyking]

I feel the pain Harry considering it will be very close indeed and i might pop down the sea front just incase i catch a few distant flashes can only hope and keep fingers crossed.